Highly moisture-sensitive electronic device element and method for fabrication

ABSTRACT

A highly moisture-sensitive element and method of making such element includes an encapsulation enclosure encapsulating all of the highly moisture-sensitive electronic devices on a substrate and a sealing material positioned between the substrate and the encapsulation enclosure to form a complete seal between the substrate and the encapsulation enclosure around each highly moisture-sensitive electronic device or around groups of highly moisture-sensitive electronic devices.

CROSS-REFEENCE TO RELATED APPLICATIONS

[0001] This is a divisional of application Ser. No. 09/957,851, filedSep. 21, 2001.

FIELD OF THE INVENTION

[0002] The present invention relates to control of moisture inside apackaged electronic device and relates particularly to highlymoisture-sensitive electronic device elements having multiple highlymoisture-sensitive electronic devices and methods for their fabricationto prevent premature device failure or premature degradation of deviceperformance.

BACKGROUND OF THE INVENTION

[0003] In manufacturing, electronic devices are typically produced byfabricating large substrates containing multiple electronic devices.These substrates are typically selected from the group consisting ofglass, plastic, metal, ceramic, and silicon or other semiconductormaterials, or combinations of these materials. The substrates may berigid or flexible and may be handled as individual units or continuousrolls. The primary reason for fabricating multiple electronic devices onlarge individual substrates or a continuous roll substrate is to reducemanufacturing cost by decreasing handling, increasing throughput, andincreasing yield. In the microelectronics industry silicon waferprocessing has increased from 2 inch wafers to 12 inch wafers resultingin significant cost reductions. In the liquid crystal display (LCD)industry glass substrate processing has increased from 300 mm×400 mmsubstrates to over 600 mm×700 mm substrates with the same result. Inmanufacturing of highly moisture-sensitive electronic devices, such asorganic light-emitting devices (OLED), polymer light-emitting devices,charge-coupled device (CCD) sensors, and micro-electro-mechanicalsensors (MEMS), the same economies of scale are achieved by fabricatinglarge individual substrates or a continuous roll substrate with multiplehighly moisture-sensitive electronic devices. FIG. 1A shows anunencapsulated highly moisture-sensitive electronic device element 14containing multiple highly moisture-sensitive electronic devices 12 onan individual substrate 10, and FIG. 1B is a schematic sectional view ofthe highly moisture-sensitive electronic device element 14 taken alongsection line 2-2 of FIG. 1A. Fabricating large individual substrates ora continuous roll substrate with multiple highly moisture-sensitiveelectronic devices, however, introduces a problem that is not importantfor less moisture-sensitive electronic devices in that highlymoisture-sensitive devices must be protected from even short termexposure to moisture during fabrication.

[0004] Typical electronic devices require humidity levels in a range ofabout 2500 to below 5000 parts per million (ppm) to prevent prematuredegradation of device performance within a specified operating and/orstorage life of the device. Control of the environment to this range ofhumidity levels within a packaged device is typically achieved byencapsulating the device or by sealing the device and a desiccant withina cover. Desiccants such as, for example, molecular sieve materials,silica gel materials, and materials commonly referred to as Drieritematerials are used to maintain the humidity level within the aboverange. Short term exposure to humidity levels greater than 2500 ppmduring the fabrication and encapsulation of these types of electronicdevices typically does not cause measurable degradation of deviceperformance. For this reason encapsulation of these types of electronicdevices is done after the electronic devices are separated from theinitial substrate.

[0005] In the manufacture of liquid crystal displays the electronics andthe liquid crystal materials are not highly moisture-sensitive;therefore, the process for encapsulating the electronics and the liquidcrystal materials does not require protection from ambient moistureduring fabrication. FIG. 2A shows a typical multiple LCD element 28before separation into single LCD devices, and FIG. 2B is a schematicsectional view of the multiple LCD element 28 taken along section line2-2 of FIG. 2A. In LCD manufacturing the LCD back-plane 22 and the LCDfront-plane 24 contain multiple LCD devices. The LCD back-plane 22 andthe LCD front-plane 24 are bonded together with a sealing material 20that surrounds each LCD device except for a gap in the sealing material20. After fabrication of the multiple LCD element 28 the LCD devices areseparated and filled with liquid crystal material. After filling the LCDdevices, the gap in the sealing material 20 is sealed with a gap sealingmaterial to retain the liquid crystal material and to protect the LCDback-plane electronics 26 and the liquid crystal material from moisture.Because LCD devices are not highly moisture-sensitive, the separationprocess of the multiple LCD element is typically performed in an ambientair environment with no measurable degradation of the LCD devices.

[0006] Particular highly moisture-sensitive electronic devices, forexample, organic light-emitting devices (OLED) or panels, polymerlight-emitting devices, charge-coupled device (CCD) sensors, andmicro-electro-mechanical sensors (MEMS) require humidity control tolevels below about 1000 ppm and some require humidity control below even100 ppm. Such low levels are not achievable with desiccants of silicagel materials and of Drierite materials. Molecular sieve materials canachieve humidity levels below 1000 ppm within an enclosure if dried at arelatively high temperature. However, molecular sieve materials have arelatively low moisture capacity at humidity levels at or below 1000ppm, and the minimum achievable humidity level of molecular sievematerials is a function of temperature within an enclosure: moistureabsorbed, for example, at room temperature, can be released into theenclosure or package during temperature cycling to higher temperature,such, as, for example, to a temperature of 100° C. Desiccants usedwithin such packaged devices include powders of metal oxides, alkalineearth metal oxides, sulfates, metal halides, or perchlorates, i.e.materials having desirably relatively low values of equilibrium minimumhumidity and high moisture capacity. However, such materials oftenchemically absorb moisture relatively slowly compared to theabove-mentioned molecular sieve, silica gel, or Drierite materials. Suchrelatively slow reaction with water vapor leads to a measurable degreeof device degradation of performance following the sealing of thedesiccant inside a device cover due to, for example, moisture absorbedon the inside of a device, moisture vapor present within the sealeddevice, and moisture permeating through the seal between the device andthe cover from the outside ambient. In addition, highlymoisture-sensitive electronic devices typically cannot be exposed tomoisture levels greater than 1000 ppm even during fabrication andencapsulation, requiring control of the moisture levels until thedevices are completely encapsulated. For these reasons control of themoisture level during fabrication and encapsulation is required toprevent degradation of performance.

[0007] To reduce the quantity of moisture absorbed on the inside of adevice or present within the sealed device, highly moisture-sensitivedevices, such as organic light-emitting devices (OLED) or panels,polymer light-emitting devices, charge-coupled device (CCD) sensors, andmicro-electro-mechanical sensors (MEMS) are often sealed within a lowhumidity environment, such as a drybox at humidity levels less than 1000ppm moisture. To ensure low levels of moisture within the sealed device,these highly moisture-sensitive devices are completely sealed within thelow humidity environment prior to any additional processing steps, suchas, bonding of interconnects, and module assembly. To achieve this lowhumidity sealing, highly moisture-sensitive devices, such ascharge-coupled device (CCD) sensors and micro-electro-mechanical sensors(MEMS), are typically sealed individually as single elements withseparate cover elements after separation from a multiple elementsubstrate or wafer. Other devices, such as organic light-emittingdevices (OLED), are sealed as multiple devices on a single element;however, in present manufacturing methods individual cover elements ofmetal or glass are used to seal each device prior to separation. FIG. 3Ashows a typical multiple OLED element 34 containing multiple OLEDdevices 32 on an individual substrate 10, encapsulated with individualencapsulation enclosures 30 and sealing material 20, and FIG. 3B is aschematic sectional view of the multiple OLED element 34 taken alongsection line 2-2 of FIG. 3A. Both of the present methods of sealinghighly moisture-sensitive devices require significant levels of handlingto assemble individual cover elements to either individual deviceelements or multiple device elements within a low moisture environment.

[0008] To reduce the handling of individual cover elements forencapsulation of multiple highly moisture-sensitive device elementswithin a low moisture environment, a modification of the LCD sealingmethod can be envisioned where the sealing material between thesubstrate and the encapsulation enclosure has no gaps prior to bonding.FIG. 4A shows a highly moisture-sensitive electronic device element 14comprising a substrate 10 containing multiple highly moisture-sensitiveelectronic devices 12, a single encapsulation enclosure 30 encapsulatingall of the highly moisture-sensitive electronic devices 12, and sealingmaterial 20. The problem with this technique is shown schematically inFIG. 4A where the sealing material 20 has been damaged by the high gaspressure inside each seal region produced when the substrate 10 and theencapsulation enclosure 30 are moved to their predetermined spacingafter both the substrate and the encapsulation enclosure have contactedthe sealing material. This damage typically appears as narrow sealwidths or even gaps in the seal, decreasing or eliminating protection ofthe highly moisture-sensitive electronic devices. FIG. 4B is a schematicsectional view of the highly moisture-sensitive electronic deviceelement 14 taken along section lines 2-2 of FIG. 4A. It would,therefore, be desirable to have highly moisture-sensitive electronicdevice elements and a method for fabricating highly moisture-sensitiveelectronic device elements that does not damage the seals that arerequired to protect the highly moisture-sensitive electronic devicesfrom moisture during fabrication and encapsulation.

[0009] Numerous publications describe methods and/or materials forcontrolling humidity levels within enclosed or encapsulated electronicdevices. For example, Kawami et al., European Patent Application EP 0776 147 A1 disclose an organic EL element enclosed in an airtightcontainer which contains a drying substance comprised of a solidcompound for chemically absorbing moisture. The drying substance isspaced from the organic EL element, and the drying substance isconsolidated in a predetermined shape by vacuum vapor deposition,sputtering, or spin-coating. Kawami et al. teach the use of thefollowing desiccants: alkali metal oxides, alkali earth metal oxides,sulfates, metal halides, and perchlorates. Kawami et al., however, donot teach a multiple EL device element with multiple airtight containersnor a method for fabricating a multiple EL device element with multipleairtight containers. The handling and sealing problems and solutions ofa multiple EL device element, such as methods to prevent damage to theseal due to high gas pressure inside the seal region duringencapsulation, are not discussed nor taught by Kawami et al.

[0010] Shores, U.S. Pat. No. 5,304,419, discloses a moisture andparticle getter for enclosures which enclose an electronic device. Aportion of an inner surface of the enclosure is coated with a pressuresensitive adhesive containing a solid desiccant.

[0011] Shores, U.S. Pat. No. 5,401,536, describes a method of providinga moisture-free enclosure for an electronic device, the enclosurecontaining a coating or adhesive with desiccant properties. The coatingor adhesive comprises a protonated alumina silicate powder dispersed ina polymer.

[0012] Shores, U.S. Pat. No. 5,591,379, discloses a moisture getteringcomposition for hermetic electronic devices. The composition is appliedas a coating or adhesive to the interior surface of a device packaging,and the composition comprises a water vapor permeable binder which hasdispersed therein a desiccant which is preferably a molecular sievematerial.

[0013] In none of these patents does Shores teach a multiple deviceelement or a method to provide moisture-free enclosures for a multipledevice element.

[0014] Booe, U.S. Pat. No. 4,081,397, describes a composition used forstabilizing the electrical and electronic properties of electrical andelectronic devices. The composition comprises alkaline earth oxides inan elastomeric matrix. Booe does not teach a multiple device element ora method used for stabilizing the electrical and electronic propertiesof a multiple electrical and electronic device element.

[0015] Inohara et al., U.S. Pat. No. 4,357,557, describe a thin-filmelectroluminescent display panel sealed by a pair of glass substratesfor protection from the environment. The method includes a protectiveliquid introduced between the glass substrates, a spacer positioned fordetermining the spacing between the pair of substrates, injection holesformed within one of the substrates to withdraw under vacuum the air andgases from the cavity defined by the substrates and to introduce theprotective liquid into the cavity, an adhesive adapted to providebonding between the substrates and the spacer, a moisture absorptivemember introduced into the protective liquid, and an adhesive to sealthe injection hole. Inohara et al. do not teach a multiple EL deviceelement with multiple airtight containers nor a method for fabricating amultiple EL device element with multiple airtight containers. Thehandling and sealing problems and solutions of a multiple EL deviceelement, such as methods to prevent damage to the seal due to high gaspressure inside the seal region during encapsulation, are not discussednor taught by Inohara et al. Although the use of injection holes in oneof the substrates will prevent damage to the seal by permitting excessambient gas to exit through the injection holes during encapsulation,Inohara et al. do not teach this purpose for providing the injectionholes. Instead the purpose of the injection holes is to allowintroduction of the protective liquid into the cavity defined by thesubstrates.

[0016] Taniguchi et al, U.S. Pat. No. 5,239,228, describe a method forprotecting a thin-film electroluminescent device similar to Inohara etal. with the additional feature of a groove in the sealing plate tocapture excess adhesive. This groove may also contain a moistureabsorption agent. Taniguchi et al. also do not teach a multiple ELdevice element with multiple airtight containers nor a method forfabricating a multiple EL device element with multiple airtightcontainers. The handling and sealing problems and solutions of amultiple EL device element, such as methods to prevent damage to theseal due to high gas pressure inside the seal region duringencapsulation, are also not discussed nor taught by Taniguchi et al.

[0017] Harvey, III et al., U.S. Pat. No. 5,771,562, describe a method ofhermetically sealing organic light emitting devices comprising the stepsof providing an organic light emitting device on a substrate,overcoating the organic light emitting device with a film of inorganicdielectric material, and sealingly engaging an inorganic layer over thedielectric material. Harvey, III et al. do not teach a multiple OLEDdevice element with multiple airtight containers nor a method forfabricating a multiple OLED device element with multiple airtightcontainers. Although the inorganic dielectric layer may providetemporary protection from moisture during the encapsulation process,Harvey, III et al. do not teach how this layer can be used to fabricatea multiple OLED device element with multiple airtight containers.

[0018] Boroson et al., U.S. Pat. No. 6,226,890, describe a method ofdesiccating an environment surrounding a highly moisture-sensitiveelectronic device sealed within an enclosure, including selecting adesiccant comprised of solid particles having a particle size range 0.1to 200 micrometers. The desiccant is selected to provide an equilibriumminimum humidity level lower than a humidity level to which the deviceis sensitive within the sealed enclosure. A binder is chosen thatmaintains or enhances the moisture absorption rate of the desiccant forblending the selected desiccant therein. The binder may be in liquidphase or dissolved in a liquid. A castable blend is formed including atleast the desiccant particles and the binder, the blend having apreferred weight fraction of the desiccant particles in the blend in arange of 10% to 90%. The blend is cast in a measured amount onto aportion of an interior surface of an enclosure to form a desiccant layerthereover, the enclosure having a sealing flange. The blend issolidified to form a solid desiccant layer, and the electronic device issealed with the enclosure along the sealing flange. Boroson et al.,however, do not teach a method of desiccating an environment surroundinga multiple highly moisture-sensitive electronic device element sealedwithin multiple enclosures.

SUMMARY OF THE INVENTION

[0019] It is the object of the present invention to provide a highlymoisture-sensitive electronic device element having highlymoisture-sensitive electronic devices and a method for fabrication ofsaid element in which damage of the moisture-sensitive electronicdevices within the element due to moisture is prevented and fabricationof said element is simplified over the present art.

[0020] In one aspect, this object is achieved by a highlymoisture-sensitive electronic device element having highlymoisture-sensitive electronic devices comprising:

[0021] a) a substrate containing two or more highly moisture-sensitiveelectronic devices;

[0022] b) an encapsulation enclosure encapsulating all of the highlymoisture-sensitive electronic devices on said substrate; and

[0023] c) sealing material positioned between said substrate and saidencapsulation enclosure to form a complete seal between said substrateand said encapsulation enclosure around each highly moisture-sensitiveelectronic device or around groups of highly moisture-sensitiveelectronic devices.

[0024] In another aspect, this object is achieved by a method of makinghighly moisture-sensitive electronic device elements having a pluralityof highly moisture-sensitive electronic devices such as OLED devices ona single substrate wherein the devices are protected from moisture priorto separating the individual devices from the substrate, comprising thesteps of:

[0025] a) placing the sealing material completely around each highlymoisture-sensitive electronic device or around groups of highlymoisture-sensitive electronic devices on the substrate or in positionson the encapsulation enclosure such that after sealing the sealingmaterial will be positioned completely around each highlymoisture-sensitive electronic device or around groups of highlymoisture-sensitive electronic devices;

[0026] b) disposing the substrate and the encapsulation enclosure, oneof which contains the sealing material, in close aligned proximity toeach other, but spaced apart, in such aligned proximate positionproviding an initial ambient pressure;

[0027] c) providing relative motion between the substrate and theencapsulation enclosure until the sealing material contacts both thesubstrate and the encapsulation enclosure and the substrate and theencapsulation enclosure are spaced apart within a predetermined range;

[0028] d) after or during step c), increasing the ambient pressure abovethe initial ambient pressure surrounding the substrate, theencapsulation enclosure, and the sealing material, to reduce thepressure difference within spaces defined between the substrate, theencapsulation enclosure, and the sealing material relative to theincreased ambient pressure, to thereby prevent deformation of thesealing material; and

[0029] e) bonding the sealing material to both the substrate and theencapsulation enclosure to form the multiple highly moisture-sensitiveelectronic device elements.

[0030] The elements and methods for fabrication of the elements inaccordance with the present invention of highly moisture-sensitiveelectronic device elements having highly moisture-sensitive electronicdevices and methods for their fabrication to prevent premature devicefailure or premature degradation of device performance provides thefollowing advantages over prior art methods: reduced handling of devicesand encapsulation enclosures by sealing all of the highlymoisture-sensitive devices on a single substrate as a single elementwith a single encapsulation enclosure encapsulating all of the highlymoisture-sensitive electronic devices on the substrate prior toseparating into smaller single or multiple device elements; improvedprotection from moisture prior to exposure to ambient environments;improved compatibility with automated processes required for high volumemanufacturing; improved compatibility with processing inside a lowmoisture environment; and reduction in encapsulation defects due topressure differentials inside and outside the highly moisture-sensitiveelectronic devices.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031]FIG. 1A shows an unencapsulated highly moisture-sensitiveelectronic device element containing multiple highly moisture-sensitiveelectronic devices on a substrate;

[0032]FIG. 1B is a schematic sectional view of the highlymoisture-sensitive electronic device element taken along section line2-2 of FIG. 1A;

[0033]FIG. 2A shows a typical multiple LCD element before separationinto single LCD devices;

[0034]FIG. 2B is a schematic sectional view of the multiple LCD elementtaken along section line 2-2 of FIG. 2A;

[0035]FIG. 3A shows a typical individually encapsulated multiple OLEDelement;

[0036]FIG. 3B is a schematic sectional view of the multiple OLED elementtaken along section line 2-2 of FIG. 3A;

[0037]FIG. 4A shows a highly moisture-sensitive electronic deviceelement comprising a single encapsulation enclosure and sealing materialwith damage due to excess pressure;

[0038]FIG. 4B is a schematic sectional view of the highlymoisture-sensitive electronic device element taken along section lines2-2 of FIG. 4A;

[0039]FIG. 5A shows a highly moisture-sensitive electronic deviceelement comprising a substrate containing multiple highlymoisture-sensitive electronic devices, a single encapsulation enclosure,and sealing material;

[0040]FIG. 5B is a schematic sectional view of the highlymoisture-sensitive electronic device element taken along section lines2-2 of FIG. 5A;

[0041]FIG. 6A shows a highly moisture-sensitive electronic deviceelement comprising a substrate containing multiple highlymoisture-sensitive electronic devices, a single encapsulation enclosure,sealing material, water absorbing material, and a temporary moistureprotection layer;

[0042]FIG. 6B is a schematic sectional view of the highlymoisture-sensitive electronic device element taken along section lines2-2 of FIG. 6A;

[0043]FIG. 7A shows a highly moisture-sensitive electronic deviceelement at an initial ambient pressure P₁, comprising a substratecontaining multiple highly moisture-sensitive electronic devices andsealing material with no gaps in close aligned proximity to, but spacedapart from, an encapsulation enclosure containing water absorbingmaterial;

[0044]FIG. 7B is a schematic sectional view of the highlymoisture-sensitive electronic device element taken along section lines2-2 of FIG. 7A;

[0045]FIG. 7C is a schematic sectional view of the highlymoisture-sensitive electronic device element taken along section lines2-2 of FIG. 7A after relative motion of the substrate and theencapsulation enclosure to the point where the sealing material contactsboth the substrate and the encapsulation enclosure and the ambientpressure is P₂;

[0046]FIG. 7D shows a highly moisture-sensitive electronic deviceelement at a final ambient pressure P₃, comprising a substratecontaining multiple highly moisture-sensitive electronic devices,sealing material, an encapsulation enclosure, and water absorbingmaterial after relative motion of the substrate and the encapsulationenclosure to a predetermined spacing; and

[0047]FIG. 7E is a schematic sectional view of the highlymoisture-sensitive electronic device element taken along section lines4-4 of FIG. 7D.

DETAILED DESCRIPTION OF THE INVENTION

[0048] The term “highly moisture-sensitive electronic device element” isemployed to designate an element that contains one or more highlymoisture-sensitive electronic devices during or after fabrication, orboth, during and after fabrication of the highly moisture-sensitiveelectronic devices is complete. The term “highly moisture-sensitiveelectronic device” is employed to designate any electronic device thatis susceptible to a measurable degradation of device performance atambient moisture levels greater than 1000 ppm. The term “substrate” isemployed to designate organic, inorganic, or combination organic andinorganic solids on which one or more highly moisture-sensitiveelectronic devices are fabricated. The term “encapsulation enclosure” isemployed to designate organic, inorganic, or combination organic andinorganic solids used to protect one or more highly moisture-sensitiveelectronic devices from moisture by preventing or limiting moisturepermeation through the encapsulation enclosures.

[0049] The term “sealing material” is employed to designate organic,inorganic, or combination organic and inorganic materials used to bondencapsulation enclosures to substrates and to protect one or more highlymoisture-sensitive electronic devices from moisture by preventing orlimiting moisture permeation through the sealing materials. The term“gap” is employed to designate a discontinuity in the sealing materialsurrounding one or more electronic devices. The term “water absorbingmaterial” is employed to designate inorganic materials used tophysically or chemically absorb or react with moisture that wouldotherwise damage the highly moisture-sensitive electronic devices. Theterm “temporary moisture protection layer” is employed to designateorganic, inorganic, or combination organic and inorganic materials usedto prevent or limit moisture induced damage to the highlymoisture-sensitive electronic devices during short term exposure toambient moisture levels greater than 1000 ppm, where short term istypically less than 10 days.

[0050] Referring now to FIG. 5A, there is shown one embodiment of thehighly moisture-sensitive electronic device element 14 in accordancewith the present invention. A highly moisture-sensitive electronicdevice element 14 is shown comprising a substrate 10 containing multiplehighly moisture-sensitive electronic devices 12, a single encapsulationenclosure 30 encapsulating all of the highly moisture-sensitiveelectronic devices 12 on the substrate 10, and sealing material 20surrounding each highly moisture-sensitive electronic device 12 with nogaps in the sealing material 20. FIG. 5B is a schematic sectional viewof the highly moisture-sensitive electronic device element 14 takenalong section lines 2-2 of FIG. 5A. In FIG. 5A and FIG. 5B, the highlymoisture-sensitive electronic device element 14 is shown comprising fourhighly moisture-sensitive electronic devices 12, but the highlymoisture-sensitive electronic device element of this invention maycomprise any number of highly moisture-sensitive electronic devicesgreater than one. By encapsulating all of the highly moisture-sensitiveelectronic devices on the substrate with a single encapsulationenclosure, the advantage of reduced handling over the prior art ofseparately encapsulating each highly moisture-sensitive electronicdevice on the substrate with separate encapsulation enclosures isachieved. The substrate 10 and the encapsulation enclosure 30 shown inFIG. 5A and FIG. 5B may be an organic solid, an inorganic solid, or acombination of organic and inorganic solids. The substrate and theencapsulation enclosure may be rigid or flexible and may be processed asseparate individual pieces, such as sheets or wafers, or as continuousrolls. Typical substrate and the encapsulation enclosure materialsinclude glass, plastic, metal, ceramic, semiconductor, metal oxide,metal nitride, metal sulfide, semiconductor oxide, semiconductornitride, semiconductor sulfide, carbon or combinations thereof. Thesubstrate and the encapsulation enclosure may be a homogeneous mixtureof materials, a composite of materials, or multiple layers of materials.The sealing material 20 shown in FIG. 5A and FIG. 5B surrounds eachindividual highly moisture-sensitive electronic device, but the sealingmaterial could also surround groups of two or more highlymoisture-sensitive electronic devices if the final product required morethan one highly moisture-sensitive electronic device within a singleelement. In addition, the sealing material surrounding each highlymoisture-sensitive electronic device or groups of highlymoisture-sensitive electronic devices contains no gaps, such that thehighly moisture-sensitive electronic device element is protected frommoisture prior to separating into smaller single or multiple deviceelements. The sealing material may be organic, inorganic, or acombination of organic and inorganic. The sealing material may be bondedto the substrate and the encapsulation enclosure by melting and coolingor by reaction curing. Typical materials bonded by melting and coolinginclude glass; hot melt adhesives such as polyolefins, polyesters,polyamides, or combinations thereof; or inorganic solders such asindium, tin, lead, silver, gold, or combinations thereof. Typicalreaction curing methods include reactions resulting from heat, radiationsuch as UV radiation, mixing of two or more components, exposure toambient moisture, removal of ambient oxygen, or combinations thereof.Typical materials bonded by reaction curing include acrylates, epoxies,polyurethanes, silicones, or combinations thereof. Other inorganicmaterial typically used in sealing materials include glass, ceramic,metal, semiconductor, metal oxide, semiconductor oxide, or combinationsthereof.

[0051] Referring now to FIG. 6A, there is shown another embodiment ofthe highly moisture-sensitive electronic device element 14 in accordancewith the present invention. A highly moisture-sensitive electronicdevice element 14 is shown comprising a substrate 10 containing multiplehighly moisture-sensitive electronic devices 12, a single encapsulationenclosure 30 encapsulating all of the highly moisture-sensitiveelectronic devices 12 on the substrate 10, sealing material 20 defininga space surrounding each highly moisture-sensitive electronic device 12with no gaps in the sealing material 20, water absorbing material 60positioned between the substrate 10 and the encapsulation enclosure 30and within the space defined by the sealing material 20, and temporarymoisture protection layers 62 coated over each of the highlymoisture-sensitive electronic devices 12. FIG. 6B is a schematicsectional view of the highly moisture-sensitive electronic deviceelement 14 taken along section lines 2-2 of FIG. 6A. Details of thehighly moisture-sensitive electronic devices 12, substrate 10,encapsulation enclosure 30, and sealing material 20 are identical withthe embodiment shown in FIG. 5A and FIG. 5B. The water absorbingmaterial is used to physically or chemically absorb or react withmoisture that would otherwise damage the highly moisture-sensitiveelectronic devices. Typical water absorbing materials include alkalinemetal oxides, alkaline earth metal oxides, sulfates, metal halides,perchlorates, molecular sieves, and metals with work functions less than4.5 eV and capable of being oxidized in the presence of moisture, orcombinations thereof. Water absorbing material may be packaged withinmoisture permeable containers or binders. The water absorbing materialmay be a single material, a homogeneous mixture of materials, acomposite of materials, or multiple layers of materials. Temporarymoisture protection layers are used to prevent or limit moisture induceddamage to the highly moisture-sensitive electronic devices during shortterm exposure to ambient moisture levels greater than 1000 ppm. Thetemporary moisture protection layer is organic material, inorganicmaterial, or a combination thereof. Typical organic materials includeepoxies, polyurethanes, polyureas, acrylates, silicones, polyamides,polyimides, phenolics, polyvinyls, phenoxies, polysulfones, polyolefins,polyesters, or combinations thereof. Typical inorganic materials includeglass, ceramic, metal, semiconductor, metal oxide, metal nitride, metalsulfide, semiconductor oxide, semiconductor nitride, semiconductorsulfide, carbon or combinations thereof. The temporary moistureprotection layer may be a single material, a homogeneous mixture ofmaterials, a composite of materials, or multiple layers of materials.

[0052] Referring now to FIGS. 7A to 7E, there is shown an embodiment ofthe method of making highly moisture-sensitive electronic deviceelements such as OLED devices on a single substrate wherein the devicesare protected from moisture prior to separating the individual devicesfrom the substrate in accordance with the present invention. FIG. 7Ashows a highly moisture-sensitive electronic device element 14 at aninitial ambient pressure P₁, comprising a substrate 10 containingmultiple highly moisture-sensitive electronic devices 12 and sealingmaterial 20 surrounding each highly moisture-sensitive electronic device12 with no gaps in the sealing material 20 in close aligned proximityto, but spaced apart from, an encapsulation enclosure 30 encapsulatingall of the highly moisture-sensitive electronic devices 12 on thesubstrate 10 and containing water absorbing material 60 in positionssuch that after bonding, the water absorbing material will be positionedwithin each moisture-sensitive electronic. FIG. 7B is a schematicsectional view of the highly moisture-sensitive electronic deviceelement 14 taken along section lines 2-2 of FIG. 7A. The initial ambientpressure P₁ may be above, below, or equal to atmospheric pressure.Details of the highly moisture-sensitive electronic devices 12,substrate 10, encapsulation enclosure 30, sealing material 20, and waterabsorbing material 60 are identical with the embodiments shown in FIGS.5A, 5B, 6A and 6B. In another embodiment, the temporary moistureprotection layer 62 described in detail in FIGS. 6A and 6B may be coatedon the highly moisture-sensitive electronic devices 12 as a replacementfor, or in addition to, the use of water absorbing material 60. In yetanother embodiment, the highly moisture-sensitive electronic deviceelement 14 comprises highly moisture-sensitive electronic devices 12, asubstrate 10, an encapsulation enclosure 30, and sealing material 20.FIG. 7C is a schematic sectional view of the highly moisture-sensitiveelectronic device element 14 taken along section lines 2-2 of FIG. 7Aafter relative motion 90 of the substrate 10 and the encapsulationenclosure 30 to the point where the sealing material 20 contacts boththe substrate 10 and the encapsulation enclosure 30 and the ambientpressure is P₂. The ambient pressure P₂ may be equal to or greater thanthe initial ambient pressure P₁. FIG. 7D shows a highlymoisture-sensitive electronic device element 14 at a final ambientpressure P₃, after relative motion between the substrate 10 and theencapsulation enclosure 30 until the substrate 10 and the encapsulationenclosure 30 are spaced apart within a predetermined range and afterbonding the sealing material 20 to both the substrate 10 and theencapsulation enclosure 30 to form the multiple highlymoisture-sensitive electronic devices 12. The ambient pressure P₃ may beequal to or greater than the ambient pressure P₂. The ambient pressureP₃ is increased, relative to the initial ambient pressure P₁ surroundingthe substrate 10, the encapsulation enclosure 30, and the sealingmaterial 20, to reduce the pressure difference within spaces definedbetween the substrate 10, the encapsulation enclosure 30, and thesealing material 20 relative to the increased ambient pressure P₃, tothereby prevent deformation of the sealing material 20. Bonding thesealing material 20 to both the substrate 10 and the encapsulationenclosure 30 may be accomplished by melting and cooling, reactioncuring, or a combination thereof. The reaction curing may includereactions resulting from heat, radiation, mixing of two or morecomponents, exposure to ambient moisture, removal of ambient oxygen, orcombinations thereof. FIG. 7E is a schematic sectional view of thehighly moisture-sensitive electronic device element taken along sectionlines 4-4 of FIG. 7D. After completing the method described in FIGS. 7Ato 7E, the highly moisture-sensitive electronic devices are typicallyseparated into individual devices or groups of devices having a portionof the initial substrate.

EXAMPLE

[0053] I. Construction of the Test Structure

[0054] A plurality of identical test structures were fabricated by thefollowing process sequence:

[0055] (1) glass substrates representing substrates containing multiplehighly moisture-sensitive electronic devices were cleaned byultrasonicating in acetone and isopropyl alcohol and rinsing indistilled water;

[0056] (2) glass encapsulation enclosures containing multiple cavitiesformed by selectively etching the glass substrate were cleaned, prior toforming a water absorbing layer, by a cleaning process identical to thesubstrate cleaning process described in step (1) above;

[0057] (3) water absorbing layers were formed and cured within thecavities of the encapsulation enclosures;

[0058] (4) sealing material was placed completely around each cavity onthe encapsulation enclosure;

[0059] (5) the substrate and the encapsulation enclosure containing thesealing material were placed in close aligned proximity to each other,but spaced apart at an initial ambient pressure;

[0060] (6) relative motion between the substrate and the encapsulationenclosure was provided until the sealing material contacted both thesubstrate and the encapsulation enclosure and the substrate and theencapsulation enclosure were spaced apart by 20-30 micrometers;

[0061] (7) after or during step (6), the ambient pressure surroundingthe substrate, the encapsulation enclosure, and the sealing material waseither increased or held constant; and

[0062] (8) the sealing material was bonding to both the substrate andthe encapsulation enclosure to form the test structure.

[0063] II. Results

[0064] The quality of the encapsulation for all locations within thetest structure was judged based on the quality of the sealing materialafter bonding. If damage was evident to the seal material due topressure differences inside and outside the sealing material, theencapsulation quality was rated as poor. If no damage was evident, theencapsulation quality was rated as good. If slight damage was evident,the encapsulation quality was rated as fair. Initial Pressure FinalPressure Seal Dimensions (Vac. gauge, (Vac. gauge, Encapsulation L × W ×T (mm) Torr) Torr) Quality 100 × 1.5 × 0.02 760 760 Poor 100 × 1.5 ×0.02 525 760 Poor 100 × 1.5 × 0.02 625 760 Poor 100 × 1.5 × 0.02 580 760Excellent 170 × 1.5 × 0.02 760 760 Poor 170 × 1.5 × 0.02 525 760 Poor170 × 1.5 × 0.02 735 760 Poor 170 × 1.5 × 0.02 625 760 Excellent

[0065] The results show that the optimal initial and final pressuredetermines the encapsulation quality and depends on the size of theencapsulation space as shown by the seal dimensions. For any particularseal dimension there will be multiple sets of initial and finalpressures that will result in high quality encapsulations, and therewill be an operating range within each set of pressures that results inhigh quality encapsulations. The conditions shown in the table show onlyone set of pressures for each seal dimension that results in highquality encapsulations.

[0066] The invention has been described in detail with particularreference to certain preferred embodiments thereof, but it will beunderstood that variations and modifications can be effected within thespirit and scope of the invention. PARTS LIST 10 substrate 12 highlymoisture-sensitive electronic device 14 highly moisture-sensitiveelectronic device element 20 sealing material 22 LCD back-planesubstrate 24 LCD front-plane substrate 26 LCD back-plane electronics 28multiple LCD element 30 encapsulation enclosure 32 OLED device 34multiple OLED element 60 water absorbing material 62 temporary moistureprotection layer 90 relative motion arrows P₁ initial ambient pressureP₂ ambient pressure when sealing material contacts both the substrateand the encapsulation enclosure P₃ ambient pressure when substrate andencapsulation enclosure are at their final predetermined spacing

What is claimed is:
 1. A method of making highly moisture-sensitiveelectronic device elements having a plurality of highlymoisture-sensitive electronic devices such as OLED devices on a singlesubstrate wherein the devices are protected from moisture prior toseparating the individual devices from the substrate, comprising thesteps of: a) placing the sealing material completely around each highlymoisture-sensitive electronic device or around groups of highlymoisture-sensitive electronic devices on the substrate or in positionson the encapsulation enclosure such that after sealing the sealingmaterial will be positioned completely around each highlymoisture-sensitive electronic device or around groups of highlymoisture-sensitive electronic devices; b) disposing the substrate andthe encapsulation enclosure, one of which contains the sealing material,in close aligned proximity to each other, but spaced apart, in suchaligned proximate position providing an initial ambient pressure; c)providing relative motion between the substrate and the encapsulationenclosure until the sealing material contacts both the substrate and theencapsulation enclosure and the substrate and the encapsulationenclosure are spaced apart within a predetermined range; d) after orduring step c), increasing the ambient pressure above the initialpressure surrounding the substrate, the encapsulation enclosure, and thesealing material, to reduce the pressure difference within spacesdefined between the substrate, the encapsulation enclosure, and thesealing material relative to the increased ambient pressure, to therebyprevent deformation of the sealing material; and e) bonding the sealingmaterial to both the substrate and the encapsulation enclosure to formthe multiple highly moisture-sensitive electronic device element.
 2. Themethod of claim 1 wherein the bonding step is accomplished by meltingand cooling, reaction curing, or a combination thereof.
 3. The method ofclaim 2 wherein the reaction includes reactions resulting from heat,radiation, mixing of two or more components, exposure to ambientmoisture, removal of ambient oxygen, or combinations thereof.
 4. Themethod of claim 1 wherein the initial ambient pressure is above, below,or equal to atmospheric pressure.
 5. The method of claim 1 wherein thesubstrate includes rigid or flexible: glass, plastic, metal, ceramic,semiconductor, metal oxide, metal nitride, metal sulfide, semiconductoroxide, semiconductor nitride, semiconductor sulfide, carbon orcombinations thereof.
 6. The method of claim 1 wherein the encapsulationenclosure includes rigid or flexible: glass, plastic, metal, ceramic,semiconductor, metal oxide, metal nitride, metal sulfide, semiconductoroxide, semiconductor nitride, semiconductor sulfide, carbon orcombinations thereof.
 7. The method of claim 1 wherein the sealingmaterial is organic material, inorganic material, or combinationsthereof.
 8. The method of claim 7 wherein the organic material isselected from the group consisting of epoxies, polyurethanes, acrylates,silicones, polyamides, polyolefins, and polyesters, or combinationsthereof.
 9. The method of claim 7 wherein the inorganic material isselected from the group consisting of glass, ceramic, metal,semiconductor, metal oxide, semiconductor oxide, and metal solder, orcombinations thereof.
 10. The method of claim 1 further including thestep of separating the highly moisture-sensitive electronic devices intoindividual devices or groups of devices having a portion of the initialsubstrate.
 11. A method of making highly moisture-sensitive electronicdevice elements having a plurality of highly moisture-sensitiveelectronic devices such as OLED devices on a single substrate whereinthe devices are protected from moisture prior to separating theindividual devices from the substrate, comprising the steps of: a)coating a substrate containing two or more highly moisture-sensitiveelectronic devices with a temporary moisture protection layer; orcoating a water absorbing material onto either the substrate or anencapsulation enclosure in positions on the substrate or on theencapsulation enclosure such that after bonding, the water absorbingmaterial will be positioned within each highly moisture-sensitiveelectronic device or within each group of highly moisture-sensitiveelectronic devices; or coating both said temporary moisture protectionlayer and said water absorbing material; b) placing the sealing materialcompletely around each highly moisture-sensitive electronic device oraround groups of highly moisture-sensitive electronic devices on thesubstrate or in positions on the encapsulation enclosure such that aftersealing the sealing material will be positioned completely around eachhighly moisture-sensitive electronic device or around groups of highlymoisture-sensitive electronic devices; c) disposing the substrate andthe encapsulation enclosure, one of which contains the sealing material,in close aligned proximity to each other, but spaced apart, in suchaligned proximate position providing an initial ambient pressure; d)providing relative motion between the substrate and the encapsulationenclosure until the sealing material contacts both the substrate and theencapsulation enclosure and the substrate and the encapsulationenclosure are spaced apart within a predetermined range; e) after orduring step d), increasing the ambient pressure above the initialpressure surrounding the substrate, the encapsulation enclosure, and thesealing material, to reduce the pressure difference within spacesdefined between the substrate, the encapsulation enclosure, and thesealing material relative to the increased ambient pressure, to therebyprevent deformation of the sealing material; and f) bonding the sealingmaterial to both the substrate and the encapsulation enclosure to formthe multiple highly moisture-sensitive electronic device elements. 12.The method of claim 11 wherein the bonding step is accomplished bymelting and cooling, reaction curing, or a combination thereof.
 13. Themethod of claim 12 wherein the reaction includes reactions resultingfrom heat, radiation, mixing of two or more components, exposure toambient moisture, removal of ambient oxygen, or combinations thereof.14. The method of claim 11 wherein the initial ambient pressure isabove, below, or equal to atmospheric pressure.
 15. The method of claim11 wherein the substrate includes rigid or flexible: glass, plastic,metal, ceramic, semiconductor, metal oxide, metal nitride, metalsulfide, semiconductor oxide, semiconductor nitride, semiconductorsulfide, carbon or combinations thereof.
 16. The method of claim 11wherein the encapsulation enclosure includes rigid or flexible: glass,plastic, metal, ceramic, semiconductor, metal oxide, metal nitride,metal sulfide, semiconductor oxide, semiconductor nitride, semiconductorsulfide, carbon or combinations thereof.
 17. The method of claim 11wherein the sealing material is organic material, inorganic material, orcombinations thereof.
 18. The method of claim 17 wherein the organicmaterial is selected from the group consisting of epoxies,polyurethanes, acrylates, silicones, polyamides, polyolefins, andpolyesters, or combinations thereof.
 19. The method of claim 17 whereinthe inorganic material is selected from the group consisting of glass,ceramic, metal, semiconductor, metal oxide, semiconductor oxide, andmetal solder, or combinations thereof.
 20. The method of claim 11further including the step of separating the highly moisture-sensitiveelectronic devices into individual devices or groups of devices having aportion of the initial substrate.
 21. The method of claim 11 wherein thewater absorbing material is selected from the group consisting ofalkaline metal oxides, alkaline earth metal oxides, sulfates, metalhalides, perchlorates, molecular sieves, and metals with work functionsless than 4.5 eV and capable of being oxidized in the presence ofmoisture, or combinations thereof.
 22. The method of claim 11 whereinthe temporary moisture protection layer is organic material, inorganicmaterial, or a combination thereof.
 23. The method of claim 22 whereinthe organic material is selected from the group consisting of epoxies,polyurethanes, polyureas, acrylates, silicones, polyamides, polyimides,phenolics, polyvinyls, phenoxies, polysulfones, polyolefins, andpolyesters, or combinations thereof.
 24. The method of claim 22 whereinthe inorganic material is selected from the group consisting of glass,ceramic, metal, semiconductor, metal oxide, metal nitride, metalsulfide, semiconductor oxide, semiconductor nitride, semiconductorsulfide, and carbon or combinations thereof.